This invention relates to a guidance system for agricultural equipment and more particularly to a guidance attachment for use with pull-type implements.
One problem confronting farmers in the operation of farm equipment is the lateral deviation of a tractor or an agricultural implement relative to a desired path when the tractor is pulling an agricultural implement through a field. Agricultural implement guidance systems are well known which utilize sensing devices that sense the position of crop rows, furrows or ridges as a reference to determine the desired path. The sensing devices typically provide an electronic output control signal corresponding to the instantaneous lateral position of the implement relative to the reference.
The output control signal serves as an input to an appropriate indicator or power guidance mechanism for assisting in or effecting the lateral positioning of the implement to an optimum operational position relative to the reference. For example, the output may drive a visible indicator observed by the operator of the implement or a towing tractor for appropriate corrective manual guidance to seek the optimum positioning of the implement. Alternatively, the output may be used as an input to an automatic power guidance mechanism for effecting automatic lateral adjustment of the implement relative to the sensed reference. One type of guidance mechanism is shown in U.S. patent application Ser. No. 07/424,701 which was filed on Oct. 20, 1989 and issued as U.S. Pat. No. 5,029,650. However, there are many types of guidance mechanisms which are well known in the art.
One known automatic power guidance mechanism is a quick attaching hitch coupler which has means for adjusting the implement attachment points to effect automatic lateral adjustment of the implement. This automatic power guidance mechanism is connected to the three point hitch of the agricultural tractor or vehicle. An implement is then mounted directly to the implement attachment points on the guidance mechanism. Implements which so utilize the three point hitch are supported completely or partially by the three point hitch. The location of the implement attachment points on the guidance mechanism correspond to the attachment points of the three point hitch of the agricultural tractor. When the implement is attached by the three attachment points, the implement is positioned in a predetermined vertical and lateral angular orientation, relative to the tractor, corresponding to the orientation of the attachment points. The guidance mechanism can accomplish lateral adjustment of the implement by changing the angular position of an outer frame which carries the implement, relative to an inner frame which is affixed to the three point hitch of the tractor. This angular adjustment steers the agricultural implement. Ground engaging tracking elements, such as fixed coulters or wheels on the implement, cause the necessary lateral adjustment as the implement moves forward at a slight angle to the direction of movement of the tractor. The necessary relative lateral movement is permitted by swinging ("sway") movement of the tractor hitch system.
However, many agricultural implements are attached to the tractor at a single free-pivoting hitch point. They are not attached in a fixed angular position as with an implement mounted on a three point hitch of an agricultural tractor. These implements are commonly referred to as "pull-type" implements because the tractor merely pulls the implement through the field.
It is an object of the present invention to provide an accessory attachment device which will allow pull-type implements to be guided with a variable angle guidance mechanism.
It is a related object to allow known variable-angle guidance systems to be used with pull-type as well as mounted or semi-mounted implements.
Another object of this invention is to provide a ground engaging guidance device for use with pull-type implements.
Yet another object of this invention is to provide an attachment device which is capable of being used on several different implements.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.